Hi folks,
I get a lot of emails from people experiencing problems when they start to sharpen. Typically, the edge is not that sharp or seems to get dull again after being sharp, during the sharpening process and edge retention is poor.
There are two issues here, the edge retention issue can be put aside, once you can effectively sharpen a knife, edge retention is not something that should stop you from using your knife, you will be able to fix that.
Here is what I normally tell people who are experiencing problems learning to sharpen.
Slow down, start from scratch and that begins with an understanding of the fundamentals.
FUNDAMENTALS:
Understand that the objective, the purpose of knife sharpening is to make a knife that no longer functions in a kitchen, function again, and to be able to do that repeatedly. That is all there is to the objective and you don't need the knife to be absolutely razor sharp to do that, you need to get it to a point where it can penetrate a tomato skin easily, effortlessly. That ability comes with an understanding of the fundamentals.
When a knife is no longer sharp, the primary edge, a very thin line running from heel to tip is no longer a thin line running from heel to tip, it is broken line, parts of the edge have folded over as a result of metal fatigue and this is perfectly normal. Sharpening involves re-establishing that primary edge by sharpening the knife at a certain angle on both sides on a whetstone until the two sides meet at the Apex. The more precisely you can do this the more refined that primary edge is until eventually it is microscopically thin and quite sharp.
You need to be able to hold an angle relatively stable, the exact angle is not as important as your ability to keep it steady as you sharpen, on BOTH sides, which is not easy at first.
Knife sharpening in my opinion falls under just two broad categories:
BURR FORMATION and BURR REMOVAL
Everything we do when we sharpen is moving us towards achieving these goals. Our goal is not to make the knife so sharp that it will slice the top of a tomato without holding the tomato, our goal, our immediate goal is to build Sharpening Muscle Memory in order for us to sharpen at a chosen angle and keep that angle steady, consistent.
Keep the process simple, you don't 20 water stones, you just need a few at the most.
You don't see me getting all hung up on water stones.
:)
Seriously though, just 2 or 3 stones is all you need and until you become pretty good at sharpening, i..e you have the basics down and you can your knives nice and sharp, just stick with a good coarse, medium and fine stone combination. I never use my 10k and up stones anymore, the most important stones in my collection are coarse stones, ones that range from 120-800 grit.
PRESSURE
It is important to understand how pressure can help you create incredibly sharp edge.
So again, Burr Formation and Burr Removal are achieved by varying levels of pressure as you sharpen.
When I pick up a knife, after inspecting it for any damage, I always start the sharpening on a coarse stone. The level of dullness and the steel will determine which coarse stone I choose and, just as importantly, what level of pressure I will begin forming the burr with.
You know by now that I use four levels of pressure on each knife with the heaviest level of pressure, P4, being the burr forming pressure. It will change, i.e. the amount of pressure I use depends on the knife, it's condition and the steel it is made from. I just don't start grinding away pressing down as hard as I can every time. Your common sense will guide you and it is something you just need to get the hang of, it isn't hard, you won't ruin your knife or anything. Making mistakes is part of the learning process, I make them all the time and what I have learned from them is what I am passing along but don't be afraid to make mistakes.
Let's say I pick up Masakage Yuki or a Fujiwara like the one in the middle in the picture above. Even though the steel in these amazing knives is very hard, it's a "good" hard and they are easy to sharpen, burr formation can be very quick so I will start one of these knives at 400 or 500 grit with moderate pressure. I always start with moderate pressure to see how the knife feels on the stone and I will adjust it, heavier, lighter or keep it the same, depending on how the burr forming is coming along. So this is something I just adjust for every knife, the one thing that is constant during this burr forming stage is that I use the heaviest level of pressure that I will use only at the burr forming stage, I start a little lighter than I think it will require, I don't want to remove metal needlessly.
After the burr has been formed on both sides, I check the condition of the edge under a light to see if I can spot any light at all. The goal is to see no light at all and if I do see even a spec of light I will return to the coarse stone with enough pressure to remove the metal causing the light reflections.
Now, since the bur is formed, it is all about burr removal and I start removing the burr, on the same coarse stone by reducing my pressure by 50% (p3) then by another 50 (%) which means the pressure is not very very light and finally, feather light pressure and a stropping motion to finish the work on the coarse stone.
(all this is shown in the sharpening videos avail on my website)
Pressure
In summary, if you are having some difficulties, stop what you are doing and then just go back to the very basics, raise a burr, make sure you are sharpening the edge of the edge, not up in the secondary bevel area and just focus on the objective.
Don't sweat angles, find a sharpening angle by holding the tip of your pinky under the knife, between the spine of the knife and the stone and that can be your angle to sharpen, to build muscle memory and strengthen your technique.
Have fun doing it as well, relax.
Peter
